Scenarios Pilot area
In total 8 scenarios for the implementation of SUDS in the pilot area were designed and implemented in the simulation models. Scenario 0 serves as the initial state, without change. In scenarios 1 – 4, the degree of implementation of SUDS is then gradually increased. In scenarios 5 – 7 individual elements are implemented.
Scenario A-0 (base scenario)
The basis of all scenarios and at the same time the base scenario (scenario A-0) is the digitised development plan of the city with an adjustment (increase) of the paved areas. This adjustment was made to correct inaccurate information in the development plan. After this adjustment, the degree of paving in scenario A-0 is 67%. In scenario A-0, a distinction is made between three types of surfaces: buildings, roads and green spaces. The roads and buildings are connected to the rainwater network.
Scenario A-1
In scenario A-1, all SUDS elements (see section Sustainable Rainwater Management) are fully implemented in the Business Campus area: all traffic-calmed roads, parking spaces and paths are modelled as permeable pavement. The roof areas are designed as green or retention roofs and are disconnected from the sewer network and connected to swale-trench elements. In addition, swale-trench elements are installed along the roads so that, depending on the topography, the surface runoff can drain into these elements.
Scenario A-2
In scenario A-2, the SUDS are gradually increased. Building on Scenario A-1 (the SUDS implemented in the Business Campus), Scenario A-2 involves the complete implementation of green and retention roofs on all roof areas with simultaneous disconnection from the sewer network.
Scenario A-3
Scenario A-3 builds on Scenario A-2, which means that in addition to the changes on the Business Campus and the green/retention roofs built into the model, Scenario A-3 also implements permeable pavement on all parking lots, paths, courtyards, side and traffic-calmed roads in the entire study area.
Scenario A-4
Scenario A-4 is the highest implementation stage with SUDS. In addition to the changes on the Business Campus, the implemented green/retention roofs and the permeable pavement, swale-trench-elements are now being implemented throughout the area. Depending on their location, the swale-trench-elements will be implemented alongside the roads within the green strips or directly on available green spaces. Depending on the location and topographical conditions, the runoff from the roads lead into the swale-trench-elements; roof surfaces are connected directly.
Scenario A-5
In scenario A-5, all roof surfaces are designed as retention roofs. In addition, the roof areas are disconnected from the sewer network. Scenario A-5 is not based on the previous scenario. This means that only the roof areas are changed.
Scenario A-6
In scenario A-6, permeable pavement is implemented in all parking lots, paths, courtyards, side and traffic-calmed roads in the entire study area. This scenario is not based on the previous scenarios, so only the change to permeable pavement is made. No additional measures are implemented.
Scenario A-7
In scenario A-7, the only SUDS measure implemented is swale-trench-elements. Here, the elements (as in scenario A-4) are installed in green strips alongside the road surfaces and in available green areas. In this scenario the roof areas are connected directly to the swale-trench elements and the roads/courtyards drain into them, depending on the location and topographical conditions.